1. Field of the Invention
The present invention relates generally to the field of tissue treatment, and more specifically to a system and method for applying reduced pressure delivered to a tissue site.
2. Description of Related Art
Clinical studies and practice have shown that providing a reduced pressure in proximity to a tissue site augments and accelerates the growth of new tissue at the tissue site. The applications of this phenomenon are numerous, but application of reduced pressure has been particularly successful in treating wounds. The treatment of wounds using reduced pressure is sometimes referred to in the medical community as “negative pressure tissue treatment,” “reduced pressure therapy,” or “vacuum therapy.” This type of treatment provides a number of benefits, including faster healing, and increased formulation of granulation tissue.
The reduced pressure at a tissue site caused by a reduced pressure treatment system may need to be properly managed to increase the effectiveness of the reduced pressure treatment. In addition, leaks and blockages in the components of the reduced pressure treatment system may need to be detected and corrected to maintain effective treatment. For example, a leak or blockage in the tube that connects a reduced pressure source, such as a vacuum pump, to the tissue site may disrupt the reduced pressure treatment being administered to the tissue site. The management or control of reduced pressure treatment systems may be generally referred to as “pump pressure control” or “differential pressure control.”
In one currently used pump pressure control system, pressure is measured at the pump outlet, i.e., the “supply pressure,” and fed into a control system that drives a pump to achieve a target pressure at the outlet of the pump. Such control systems utilize a pressure sensor to measure the supply pressure being delivered at the outlet of the pump. Another currently used pump pressure control system also measures the pressure in proximity to the tissue site, i.e., the “applied pressure” utilizing a second pressure sensor close to the tissue site. A control system may be also programmed to compare the supply pressure to the applied pressure to determine the difference in pressure, i.e., the “applied differential pressure” between them. The applied differential pressure provides information about leaks or blockages that occur between the tissue site and the pump.
Currently used differential pressure control systems employ two sensors to measuring pressure at both the pump outlet and at the tissue site. The pressures measured by the two sensors are compared so that the occurrence of leaks or blockages in reduced pressure treatment system may be identified. However, the two sensors used by current differential pressure control systems increase the size, weight, cost, and complexity of such systems. For example, the use of two sensors increases the amount of electronic circuitry and power used by the reduced pressure treatment system. In addition, comparing measurements from two different sensors requires that the reduced pressure treatment system include circuitry and software for making the comparison. The additional components required by current differential pressure control systems reduce the ability of those systems to be used to treat low-severity wounds and wounds on ambulatory patients. In addition, the additional components required by such systems increase the obtrusiveness and weight of the reduced pressure treatment system, thereby increasing the discomfort and limiting the mobility of the patient. Discrete pressure sensors for providing feedback to the system are not only expensive, but also increase the potential for wound infection as another input connected to the pneumatic circuit of the negative pressure wound care system.